This invention relates to mechanisms for mounting an axle to a vehicle frame.
A first type of axle mounting mechanism is described in U.S. Pat. No. 4,706,770 and includes four rear wheels which are driven by the vehicle's power source. Chains operatively link the front driven wheels with respective rear driven wheels. As best seen in FIGS. 2 and 3 of '770, axle support structures referred to by numerals 28, 30, 32 and 34 extend outwardly from the main frame members and serve to rotatably support respective axles. The axle support structures are welded to the main frame, and carry bearings which receive the respective axles. Inherent inaccuracies in the welding process and tolerance buildups can accumulate such that the axle support structure may actually carry the axle in misaligned position with respect to the differential shafts. Undesirable wear can occur between parts when excessive misalignment occurs. The axle assemblies are relatively exposed, such that rust or other deterioration may occur on the various parts after prolonged use. When service is required, as for maintenance or replacement of a bearing or axle, the axle must be forced out from within the bearings, and disassembly or re-assembly may be difficult if the various parts are in a deteriorated condition. Furthermore, a separate idler mechanism is typically provided for tightening or tensioning the drive chain during vehicle operation.
Another type of axle mounting mechanism provides an enclosed axle support which is bolted directly to the housing of the transmission, and extends from the transmission to a location just inboard of the wheel. The axle support houses bearings which rotatably receive the axle. Alignment of the axle with the transmission output shaft is relatively accurate, since the mounting mechanism is bolted directly to the transmission housing. However, since the axle support mechanism is entirely enclosed, a mechanism such as a sprocket and chain can not be coupled to the axle in a manner as shown in U.S. Pat. No. 4,706,770 for transmitting rotational motion to another axle.
It would therefore be desirable to provide an axle support and mounting mechanism which serves to accurately align the axle with the vehicle's transmission output shaft. It would be desirable for such a mechanism to be composed of relatively few parts and be easily assembled. It would be desirable for such a mechanism to generally prevent rust and deterioration of the axle, and allow the mechanism to be easily disassembled and re-assembled for maintenance purposes. It would be desirable for such a mechanism to allow for four wheel drive operation, and include parts that could also be assembled in a two wheel drive configuration. It would be desirable for such a mechanism to include an adjustable chain tensioning mechanism comprised of relatively few parts, and simple in construction such that manufacture and assembly costs are relatively low.